fundament vs tail end

fundament and tail end both are nouns.

Word	Noun	Adjective	Verb	Adverb
fundament	Yes	No	No	No
tail end	Yes	No	No	No

As nouns, fundament and tail end are synonyms defined as:

fundament and tail end: the fleshy part of the human body that you sit on

fundament (noun)	tail end (noun)
lowest support of a structure	the fleshy part of the human body that you sit on
the fleshy part of the human body that you sit on	any projection that resembles the tail of an animal
the fundamental assumptions from which something is begun or developed or calculated or explained	the time of the last part of something